'\" et
.TH MBSTOWCS "3P" 2017 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\"
.SH PROLOG
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
.\"
.SH NAME
mbstowcs
\(em convert a character string to a wide-character string
.SH SYNOPSIS
.LP
.nf
#include <stdlib.h>
.P
size_t mbstowcs(wchar_t *restrict \fIpwcs\fP, const char *restrict \fIs\fP,
    size_t \fIn\fP);
.fi
.SH DESCRIPTION
The functionality described on this reference page is aligned with the
ISO\ C standard. Any conflict between the requirements described here and the
ISO\ C standard is unintentional. This volume of POSIX.1\(hy2017 defers to the ISO\ C standard.
.P
The
\fImbstowcs\fR()
function shall convert a sequence of characters that begins in the
initial shift state from the array pointed to by
.IR s
into a sequence of corresponding wide-character codes and shall store
not more than
.IR n
wide-character codes into the array pointed to by
.IR pwcs .
No characters that follow a null byte (which is converted into a
wide-character code with value 0) shall be examined or converted. Each
character shall be converted as if by a call to
\fImbtowc\fR(),
except that the shift state of
\fImbtowc\fR()
is not affected.
.P
No more than
.IR n
elements shall be modified in the array pointed to by
.IR pwcs .
If copying takes place between objects that overlap, the behavior is
undefined.
.P
The behavior of this function shall be affected by the
.IR LC_CTYPE
category of the current locale.
If
.IR pwcs
is a null pointer,
\fImbstowcs\fR()
shall return the length required to convert the entire array regardless
of the value of
.IR n ,
but no values are stored.
.SH "RETURN VALUE"
If an invalid character is encountered,
\fImbstowcs\fR()
shall return (\fBsize_t\fP)\-1
and shall set
.IR errno
to indicate the error.
.P
Otherwise,
\fImbstowcs\fR()
shall return the number of the array elements modified
(or required if
.IR pwcs
is null),
not including a terminating 0 code, if any. The array shall
not be zero-terminated if the value returned is
.IR n .
.SH ERRORS
The
\fImbstowcs\fR()
function shall fail if:
.TP
.BR EILSEQ
An invalid character sequence is detected. In the POSIX locale an
.BR [EILSEQ] 
error cannot occur since all byte values are valid characters.
.LP
.IR "The following sections are informative."
.SH EXAMPLES
None.
.SH "APPLICATION USAGE"
None.
.SH RATIONALE
None.
.SH "FUTURE DIRECTIONS"
None.
.SH "SEE ALSO"
.IR "\fImblen\fR\^(\|)",
.IR "\fImbtowc\fR\^(\|)",
.IR "\fIwctomb\fR\^(\|)",
.IR "\fIwcstombs\fR\^(\|)"
.P
The Base Definitions volume of POSIX.1\(hy2017,
.IR "\fB<stdlib.h>\fP"
.\"
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1-2017, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, 2018 Edition,
Copyright (C) 2018 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
In the event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .
.PP
Any typographical or formatting errors that appear
in this page are most likely
to have been introduced during the conversion of the source files to
man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
